Wave generation and control



S. M. BELESKAS WAVE GENERATION AND CONTROL Jul 11, 1950 Filed Oct. 51, 1945 Sheets-Sheet 1 Fig.1.

m M w 0 CAPA C/T'Y-MMF- c1 l I 10 3O Fig. 1a.

INVENTOR. STANLEY A4- BELES/(AS A TTQRNE'V July 11, 1950 s. M. BELESKAS WAVE GENERATION AND common 3 Sheets-Sheet 2 Filed o t. :51, 1945 OUTPUT M OD ULA T/ON lNPUT' OUTPUT MODULA T/ON NPU T INVENTOR. STANLEY M. BELESKAS #44 ATTORNEY July 11, 1950 s. M. BELESKAS WAVE GENERATION AND CONTROL 3 Sheets-Sheet 3 Filed Oct. 31, 1945 rbbbbv wkQIu uQ W J INVENTOR. STANLEY M 5ELES/64S A TTORNEY Patented July 11, 1950 2,515,030 WAVE GENERATION AND CONTROL Stanley M. Beleskas; oaklyn, N. 1., magnolto Radio Corporation of America, a corporation of Delaware Application October 31.1945, Serial No. 625,889

9 Claims.

This application concerns an improved wave generating, wave frequency stabilizing and wave frequency controlling system.

An object of my invention is the generation of stabilized oscillatory energy, the stabilized frequency of which may be varied over a wide frequency range and the amplitude or intensity of hich is substantially constant throughout the E ,inge of operation.

An additional object of my invention is oscillation generation as described in the preceding additional objects are attained will be apparent in the detailed description which follows. In this description reference will be made to the attached drawings, wherein Fig. 1 illustrates by circuit diagram the essential features of a stabilized oscillation generator arranged in accordance with my invention.

A feature of this embodiment is a variable reactance incorporated therein by means of which the frequency of the stabilized generated oscillations may be varied through a wide range and yet remain of substantially constant amplitude and of substantially constant mean frequency.

Fig. 2 illustrates by circuit diagram the essential features of my improved stabilized wave generator of Fig. l, incorporated with an improved variable reactance which itself may be controlled by control potentials or signals to control or modulate the timing of the generated oscillations.

Fig. 1a is a curve illustrating the operation of the generator of Fig. 1, and in particular the relation between frequency change of the generated wave and changes in the reactance causing the said frequency change.

Fig. 2a. is a vector diagram showing the relation of voltages appearing in the controllable reactance of Fi 2.

Figs. 3 and illustrate modifications of the embodiment illustrated in Fig. 1.

In Fig. 1', tube or electron control device Tl has its screening electrode or equivalent electrode 6 regeneratively coupled by a coupling condenser C3 and a crystal X to the control electrode or grid Ill. The'grid electrode 6 is coupled to the cathode or electron-emitting electrode by condenser 02, while the grid electrode III is coupled to the cathode by a variable condenser Cl. Resistance RI supplies direct current biasing potential to the control grid l0, resistance R2 supplies positive potential to the grid 6 and the tube output impedance Z supplies positive potential to the anode of the tube.

Oscillations are generated in the circuits including crystal x, condensers Cl and C2. and

electrodes 6 and Ill, by virtue of the regenerative coupling from the electrode 6 serving as the generator anode or electron-receiving. electrode through the crystal to the control grid Ill. The

generated voltages are of substantially constant frequency because of the stabilizing eflect of the crystal X which to a large extent determines the frequency of operation. The generated OSClllfl-x tions are electron coupled through the tube to the plate and are supplied at the output leads. If a capacitor C2, which may be fixed, is connected between screen and cathode and a variable capacitor Cl is connected between grid l0 and cathode, the frequency of the oscillations generated can be varied over a very wide range without upsetting the stability of the oscillator. The output stays substantially constant throughout the entire range of variation. Similar results are obtained if Cl is fixed and C2 is varied. Operation and comparison has shown that by usingthe improved means of my invention the frequency generated may be varied as much as two times more than any other system used, without changing the stability of the oscillator. As the frequency of operation is increased the range of variation is increased. At higher frequencies the range of variation is more than twice as great as can be obtained in other systems without reducing the stability. The generated oscillations are stabilized in the usual manner by the crystal X.

Other systems which employ a variable capacitor across the crystal or have a variable air gap on the crystal cannot vary the frequency, more than .01 At this variation the oscillators known heretofore usually stop oscillating or become unstable with a reduced output. In my improved generator variations in the frequency of the generated oscillations of .025% were obtained.

In Fig. 1a I have illustrated graphically the frequency change of the generated oscillations in percent plotted as ordinates against the capacity change at CI (abscissae) necessary or required to produce the frequency change.

In an embodiment which proved entirely successful the tube Ti is a type 6SJ'Z C l =0-l00 mmf. C2=100 mmf.

C3 =390 mmf.

R l =330,000 ohms R2=82,000 ohms and the crystal frequencies used were within these frequencies =800 kc. to 2333 kc.

As stated above by varying Cl stabilized oscillations of a wide range of frequencies may be developed and supplied electronically to the output circuit,

In Fig. 2 I have shown a variable reactance Cl which may be adjusted to change the frequency of the oscillations generated or may be controlled by control potentials to change the frequency of the oscillations generated in accordance with control potentials or the reactance may be modulated in accordance with signals to modulate the timing of the oscillations generated.

In Fig. 2, Cl, shown dotted, is mainly made up of the reactance between the anode and cathode of a reactance tube or electron discharge device T2 having its anode l4 coupled by coupling and direct current blocking condenser C4 to the control grid In of tube TI and its cathode coupled to the cathode of tube TI. The anode of T2 is coupled to a direct current source by inductance Ll. The control grid I6 of'tube T2 is coupled by a phase shifting, coupling and direct current potential blocking condenser C to the anode of tube T2 so that oscillations of the generated frequency are supplied from the oscillatory circuit, at one terminal of the crystal X, to the control grid IS. The control grid I6 is coupled to the cathode of tube T2 by a phase shifting resistance R3 and inductance L2.

The condenser C5, resistance R3 and inductance L2 form a phase shifting network the purpose of which is to apply to the control grid It a voltage of the generated frequency which leads the voltage of the generated frequency on the anode I4 by about 90 so that the current through the tube leads the current in the oscillation generator and the tube T2 simulates a capacitive reactance. If the impedance of capacitor C5 is made high as compared to the resistance of the resistor R3 then the alternating current through the circuit and in particular through the resistance R3 will lead the voltage of the generated frequency applied across the network, that is, across the anode and cathode of tube T2 by about 90.

Since the current through R3 leads the applied voltage by about 90 the voltage on the control grid 16 at the generated frequency leads the anode voltage by the same amount, so that current through the tube is advanced in phase about 90 with respect to the anode voltage. If the current through the network does not lead the voltage thereacross by 90 the desired 90 relation between the anode voltage and tube current is not obtained. To obtain an exact 90 phase displacement of the grid voltage an inductance L2 is introduced to provide a voltage component which lags or opposes the voltage component across C5 by an amount such that the voltage drop across R3 can be made exactly 90 with respect to the applied voltage, or more than 90, or less than 90.

In a particular application to provide an exact 90 phase shift the impedance of L2 is made to equal the resistance of R3 and both equal /2 the impedance of C5. The vector relation then would be as shown in Fig. 21;, wherein ep is the voltage from the plate-ll to ground, eg is the voltage between the grid [6 and ground, 1R3 is the drop through R3, mm is the drop through L2, and izC5 is the drop across C5. C3 and C4 are only blocking condensers.

In any event, the tube T2 simulates a reactance the size of which depends upon the intensity of the current through the tube and which r'eactance is capacitive in character. This will provide in the tube T2 a reactive effect capacitive in nature and this effect, as stated above, is utilized as the variable capacity CI of the oscillator. By varying the potential of grid IS the out-ofphase current in the tube T2 supplied to the anode I4 is varied, thereby varying the size of the simulated capacity between the output electrodes of tube T2. This'varies the frequency of the oscillations generated, as stated above in detail in connection with Fig. 1.

If the potential applied to It is changed the frequency of the oscillations generated changes. Control potentials of any nature, such as, for example, potentials derived for automatic frequency control purposes or modulating potentials, may be applied to the control grid l6.

Returning now to the generator of Fig. 1, the frequency of operation may be changed by changing the value of CI or by varying the value of C2. In Fig. 2, I have shown'a capacity Cl which is variable and a fixed capacity C2.

In the embodiment of Fig. 3, I have shown the capacity Cl as being fixed and the capacity C2 as being variable. Moreover, in this figure the capacity C2 comprises the tube reactance T2. The operation of the arrangement'in Fig. 3, it is believed, is self-evident from the foregoing description, and from the drawings, wherein similar reference characters primed have been used in the reactance tube circuit. In the arrangement of Fig. 3, the tube T2 again has its control grid l6 excited by oscillations of the generated frequency advanced in phase 90 with respect to the oscillations of the generated frequency on the anode H of the reactance tube and on the screening electrode 6 of the generator tube. The current in the tube T2 to the anode leads the anode voltage by 90 and the tube T2 simulates a capacity connected between the oscillator anode 6 and the cathode of the oscillator.

By changing the potential on the contgol grid IS the current through the tube is changed, thereby changing the value of the simulated capacity. The control potential may be changed as desired to change the frequency of operation of tlge generator as described in connection with Fig.

In the embodiment of Fig. 4, I have shown two simulated reactances comprising tubes T2 and T2. In this embodiment the tube T2 is arranged as in Fig. 2, to provide a simulated capacity equivalent to the capacity CI in Fig. 1. The tube T2 is arranged as in Fig. 3, to provide a simulated reactance equivalent to the reactance C2 of Fig. 3. The individual reactance tubes operate as in Figs. 2 and 3. As to their combined eiIect note that the anodes of tubes T2 and T2 operate at opposed radio frequency-voltages, and in each reactance tube a reactive effect is produced. Moreover, the tube reactive effects must increase and decrease together. Control or modulation is accordingly applied in like phase to the tubes T2 and T2.

What is claimed is:

1. In a wave generatin circuit to be used with an electron control device having oscillation generating electrodes including an electron-emitting electrode. an electron-receiving electrode and a control electrode, a piezoelectric crystal regeneratively coupled substantially directly between said receiving electrode and said control electrode, a frequency-determining capacitor connecting said control electrode substantially dia 5 means for varying the eifective capacitance of said one capacitor to frequency modulate the oscillations generated.

2. A wave generating circuit according to claim connecting the receiving electrode to the emitting electrode.

4. A wave generating circuit according to claim 1, wherein the capacitances of both capacitors are variable in response to signals and including signal-responsive means for varying the effective capacitances' of both capacitors.

5'. In a wave generating circuit to be used with an electron control device having oscillation generating electrodes including an electron-emitting electrode, and electron-receivingelectrode and a control electrode, a piezoelectric crystal regeneratively coupled substantially directly between said receiving electrode and said control electrode, a frequency-determining capacitor connecting said control electrode substantially directly to. said emitting electrode. a frequencydetermining capacitor connecting said receiving electrode substantially directly to said emitting electrode, at least one of said capacitors being comprised of the reactive effect produced between the output electrodes of an electron discharge device with connections arranged for applying oscillatory energy in phase displaced relation to an output electrode and control electrode of said discharge device, means for applying direct op-- generated, and means for varying the current" through said discharge device to varythe eifec- 6 tive capacitance of said one capacitor to frequency modulate the oscillations generated.

8. Awave generating circuit according to claim 5, wherein said one capacitor is the capacitor connecting the control electrode to the emitting electrode of the control device. 1

7. A wave generating circuit according to claim 5, wherein said one capacitor is the capacitor connecting the receiving electrode to the emitting electrode of the control device.

8. A wave generating circuit according to claim 5, wherein both capacitors are comprised of the 'reactive effects produced between the output REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Crosby June 18, 1946 

